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Astronauts Need Their Rest Too STS–107: Space Research And

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Astronauts Need Their Rest Too STS–107: Space Research And National Aeronautics and Space Administration STS–107: Space Research and You Astronauts Need Their Rest Too Sleep-Wake Actigraphy and Light Exposure During Space Flight The success and effectiveness of human space flight depends on astronauts’ ability to maintain a high level of cognitive performance and vigilance. This alert state ensures the proper operation of sophisticated instrumentation. An important way for humans to remedy fatigue and maintain alert- ness is to get plenty of rest. Astronauts, however, commonly experience difficulty sleeping while in space. During flight, they may also experience disruption of the body’s circadian rhythm — the natural phases the body goes through every day as we oscillate between states of high activity dur- Scott Altman, mission commander for STS–109, sleeps on ing the waking day and recuperation, rest, and the flight deck of the Space Shuttle Columbia. repair during nighttime sleep. Both of these factors are The results of this research could lead to the associated with impairment of alertness and per- development of a new treatment for sleep distur- formance, which could have important consequences bances, enabling crewmembers to avoid the during a mission in space. decrements in alertness and performance due to The human body was designed to sleep at sleep deprivation. What we learn about sleep in night and be alert and active during the day. We space informs treatment for earthbound popula- receive these cues from the time of day or amount tions, such as the elderly and insomniacs, who of light, such as the rising or setting of the sun. experience frequent sleep disturbances or altered However, in the environment of the Space Shuttle sleep patterns. or the International Space Station where light lev- els are highly variable, the characteristics of a Earth Benefits and Applications 24-hour light/dark cycle are not present to cue This research could benefit the health, productivity, and safety of the astronauts’ bodies about what time of the day certain earthbound populations with similar conditions: • Insomniacs it is. Astronauts orbiting Earth see a sunset and • Shift workers sunrise every 90 minutes, sending potentially dis- • The elderly ruptive signals to the area of the brain that • Travelers with jetlag. regulates sleep. On STS–107, researchers will measure sleep- wake activity with state-of-the-art technology to quantify how much sleep astronauts obtain in space. Because light is the most powerful time cue to the body’s circadian system, individual light exposure patterns of the astronauts will also be monitored to determine if light exposure is associated with sleep disruption. Principal Investigator: Dr. Charles Czeisler, Brigham and Women's Hospital, Harvard Medical School, Boston, MA Project Scientist: Dr. Jacob Bloomberg, Johnson Space Center, Houston, TX Project Manager: Angie Lee, Johnson Space Center, Houston, TX http://spaceresearch.nasa.gov Background Information Science Astronauts will wear a light-recording and activity- Operations monitoring device called the Actilight watch for the The crewmembers will don their Actilight watches as duration of the mission. Data on sleep-wake activity and soon as possible in flight, and simply wear them continu- light exposure patterns obtained during flight will be com- ously on their non-dominant wrists outside of their sleeves. pared with those measured for two weeks on Earth, The watches can be removed temporarily for specific activ- ities, such as a spacewalk. Upon landing they will turn in the watches for analysis. In addition, each crewmember will complete a sleep log every day, recording how long they slept and rating the quality of sleep and how alert they feel. Baseline data will be collected before and after the flight using the same methods. Comparison of the data obtained in flight to baseline data will indicate to scient- ists the changes in astronauts’ sleep-wake cycle and light exposure patterns. Earlier Results The results of previous research on both short- and long-duration space missions suggest that approximately 25 percent of crewmembers The sun rises over Earth in this photo taken during STS–101 (the rear experience dramatic impair- of the Space Shuttle Atlantis is silhouetted in the foreground). The ment of amount and/or quality Shuttle environment has highly variable light levels, a factor possibly of sleep. Hypnotic medica- contributing to astronauts’ sleeping difficulties. tions are the most frequently administered medications after approximately 90 days prior to the first several days in flight. flight. This will allow researchers This suggests that insomnia is to compare how much the astro- a prevalent symptom among nauts slept in space versus how astronauts. Despite these data, much they sleep normally. Astro- little is known of the cause, nauts will also wear the Actilight prevalence, or severity of watch for the 11 days immediately sleep disruption during short- Shown is an actiwatch, similar prior to launch to determine if duration missions and less is to the model that STS–107 astronauts sleep less prior to flight. known about the effects on astronauts will don. Recovery from space flight will sleep during long-duration also be assessed for one week fol- missions. Scientists hope that deeper understanding of lowing landing. sleep disturbances in space will lead to the development Each astronaut will also fill of treatments to help astronauts, as well as those who Astronauts of STS–51 are out a sleep log each morning. The experience sleep disorders on Earth. caught during a sleep logs are their subjective evaluation period in the Shuttle of the amount and quality of sleep. Discovery’s middeck. If an astronaut reports that his or her sleep was disturbed, questions in the log address the cause of the disturbance. The astro- nauts will also report how much caffeine they consumed or if they took medication, as both could impact sleep. Hardware The Actilight watch and a sleep log will be used for each astronaut in the study. The Actilight watch is a flight- approved version of the Actiwatch-L product, made by Columbia Mini-Mitter, Inc. This device resembles a small wristwatch and measures the wearer’s activity and exposure to ambient light. It is powered by a lithium manganese battery and can record data for about 30 days. The sleep log is a hard Approximate location of this payload aboard STS–107. copy booklet. FS-2002-04-059-JSC.
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